Caplet was a composer in his own right, whose works have been overlooked for the most part in the modern repertoire. Especially interesting is his instrumental use of voices, as in his Septuor à cordes vocales et instrumentales from 1909 and in the oratorio-like Le Miroir de Jésus from 1923, which features "choeur de femmes" in an accompanying role Caplet termed "voix d'accompagnement". He also wrote two works based on the short story The Mask of the Red Death by Edgar Allan Poe: Conte fantastique for harp and string quartet, and an orchestral symphonic study Le Masque de la mort rouge.

Myrrha, (text by Fernand Beissier) cantata for second round competition of the Prix de Rome, July 1901 - Caplet won first prize, also set by Ravel and other second round contestants. Performed in Le Havre November 1901.[4]

^Revue belge de musicologie: - Volumes 36 à 38 - Page 166 1982 "On Sunday, November 24 (a matinee concert) a Festival Caplet was held in the Théatre Cirque.... The principal work which was presented was his prize-winning cantata Myrrha."

Bernac, Pierre. The Interpretation of French Song. New York: Norton, 1978.